1. Field of the Invention
The present invention relates to an information storage apparatus which receives and stores content distributed by broadcasting.
2. Description of the Related Art
Recent popularization of digital broadcasting increases demand for expansion of broadcasting services. One of such services may be a server-type broadcasting service.
The server-type broadcasting service is a system which enables a user to use various contents associated with broadcast programs by using a function of a home server (large-capacity storage apparatus for storing programs and various pieces of information provided via digital broadcasting or Internet according to viewer's preference) that is connected to not only digital broadcast programs but also the Internet.
The server-type broadcasting service uses a conditional access system for playback (CAS-P) as a conditional access system (CAS). In the conditional access system for playback, contents stored in an encrypted status in a storage unit of a receiver are decrypted during reproduction to enable a user to view and use the contents according to use conditions permitted by a provider who distributes the contents.
The server-type broadcasting service has a feature that broadcasts can be used in a form of a database or archives by providing broadcast contents as contents to a storage area in a server-type broadcast receiver owned by the user.
In the server-type broadcasting service, there is a demand for contents storage which effectively uses a limited storage area. Demand for the server-type broadcasting service and, together with an increase in data size caused by recent achievement of higher definition of digital broadcast contents, demand for a technology which efficiently uses the storage area by deleting unnecessary stored contents have increased.
As an example of efficiently using the storage area, Japanese Patent Application Laid-Open No. 2000-165788 discuses a digital broadcast receiving terminal apparatus which presets a threshold value of a set usable amount of a hard disk drive (HDD) at an end of recording of a program. The digital broadcast receiving terminal apparatus compares the usable amount with the threshold value to display a message indicating that a usable capacity is at a low level if it is detected that the usable amount is small, and simultaneously displays a value of the usable capacity when necessary. The digital broadcast receiving terminal apparatus sets expiration time of a recorded program and automatically deletes an expired program.
However, the digital broadcast receiving terminal apparatus of Japanese Patent Application Laid-Open No. 2000-165788 cannot delete a program yet to expire at a time of making a reservation of recording target contents, since the digital broadcast receiving terminal apparatus automatically deletes the stored contents only when the expiration time set for the programs passes. Consequently, contents that have expired by the recording start time are kept stored, and efficient use of the storage area cannot be achieved.